A hybrid vehicle comprises an internal combustion thermal engine, which transmits torque to the driving wheels by means of a transmission provided with a gearbox, and at least one electric machine which is supplied by an electronic power converter and is mechanically connected to the driving wheels. The electric machine is controlled by an electric control connected to an electric storage system typically consisting of a chemical battery pack possibly parallel connected to one or more super-capacitors.
When the vehicle is running, the following may occur: a heat operating mode, in which the torque is generated by the thermal engine only, and the electric machine possibly operates as a generator to recharge the electric storage system; an electric operating mode, in which the thermal engine is switched off and the torque is generated by the electric machine operating as an engine only; or a combined operating mode, in which the torque is generated both by the thermal engine and by the electric machine operating as an engine. Moreover, to increase the overall energy efficiency during all deceleration steps, the electric machine may be used as a generator to carry out a regenerative deceleration in which the kinetic energy held by the vehicle is partially converted into electric energy which is stored in the electric storage system, rather than being completely dissipated into friction.
The placement of the electric machine inside the vehicle, and therefore, the mechanical connection of the electric machine to the driving wheels may be very complex in an existing vehicle, as finding the space required to house the electric machine is generally very difficult in an existing vehicle which has not been specifically designed for hybrid drive. Accordingly, modifying an existing vehicle to make the vehicle itself hybrid is often impossible; such a limitation is particularly serious as it does not permit to produce a hybrid vehicle from an existing vehicle of conventional type, but it requires a completely new design of the hybrid vehicle. Accordingly, the design and development costs of a hybrid vehicle are high, thus making the hybrid vehicles not very economically affordable on the market.
A hybrid vehicle comprises a cooling system, which the present inventors have recognized should be capable of cooling both the thermal engine, and the electric machine. The cooling system is generally complex and cumbersome, and especially difficult to be installed when the vehicle is not created for hybrid drive from the beginning, but is obtained by adding an electric machine to an existing vehicle with thermal drive alone.
Another problem which occurs in a hybrid vehicle created by adding an electric machine to an existing vehicle with thermal drive alone is how to activate the auxiliary devices (e.g. the servo-brake pump, the power steering pump, the air conditioner compressor . . . ) in case of purely electric drive or when the vehicle is stopped in “Start&Stop” mode (e.g., when thermal engine 5 is switched off), as all the auxiliary devices take the motion from the drive shaft of the thermal engine.
US2004261753A1 discusses a vehicle with hybrid drive having: a thermal engine provided with a drive shaft; a reversible electric machine; an auxiliary device consisting of an air conditioner compressor; a mechanical belt transmission which connects the electric machine, the auxiliary device and the drive shaft of the thermal engine to one another; and a freewheel interposed between the mechanical transmission and the drive shaft of the thermal engine.
Overview
It can be an object of the present invention to provide a hybrid vehicle, which is free from the above-described drawbacks while being easy and cost-effective to be implemented.
According to an embodiment of the present invention, a hybrid vehicle is provided as claimed in the attached claims.